single downdraught carb mainfold for 18rg????

[mike1980ra40]

I know this might sound like a crazy idea and a real step backwards in performance
Im looking at doing this on mine (270 head) put my 18RC niki carb on the 18rg
is there anything around or could be made ?

[river]

Hi,

You're right, it is a crazy idea.

However, to answer your question... I don't know of any manifolds around that would secure a down draught single carby to an 18R-G. I suppose you could get one custom made, but it would probably cost more than a set of side draught Solex and wouldn't have the same performance.

Why are you thinking of doing such a thing?

seeyuzz
river

[The Witzl]

i think i have at least 2, maybe 3 18RG intake manifolds....

[o_man_ra23]

why oh why oh why??

Is there a down draught carby that an 18RG will run properly on?? Something that provides a fair bit of evenly distributed airflow...

The niki carb will probably provide enuf flow for idle... maybe even River stylz RPM... but to feed the hungry top end of the 18RG rev range, you just need the short runner solexes which are more funner. (bitta crap poetry for yas). In the end, you will probably get the shits with not being able to rev, and your engine will get the shits with running lean. Did you know that the carby is actually the restriction point in the 18RC??

Cheers, Owen

[mike1980ra40]

I thought it might be a crazy idea, I know fiat 124 has them, and I have seen the odd
single side draught manifold here and there for 2tg and 3tg (a lynx one) to run a single
solex/weber/delloreto. i was wondering if there was anything like that for an rg.

why think of such a thing, i know rg's are a hungry motor, remember the movie "piranha"
my rg is a killer piranha that hasn't eaten in six months.
the other thing was parts for solex are to hard to get and weber's, parts are more accessible.

cheerz

[o_man_ra23]

ask Rodger from these forums about solex parts, he has them coming out of his a-hole.

Cheers, Owen

[mike1980ra40]

he has them coming out of his a-hole. Cheers, Owen

that cracks me up ... i will do that. I'm still interested in experimenting with a single
carb. on a slighty OT subject .. found out corolla ecu's can be used on rg's ..

cheerz

[MWP]

Is there a down draught carby that an 18RG will run properly on?? Something that provides a fair bit of evenly distributed airflow...

Why would the 18RG be different from any other engine?
Is there something about it that makes it more picky about even air flow compared to any other engine?

[o_man_ra23]

Any ECU can be used on an RG... as long as it takes the correct inputs, gives the correct type of injector/cold start outputs, and has the correct air/fuel calculations. I would be wary of using an ECU from a different engine though, as a wrong mixture can give you evil results. You would be better using something like a MegaSquirt or Adaptronic or etc. aftermarket ECU and programming it accordingly.

Cheers, Owen

[mike1980ra40]

dont know about every one else RG, mine is real finicky.

[o_man_ra23]

MWP, its called lumpy cams. These engine work best with virtually zero runners (ITBs), so anything hampering the flow will net a bad result... and your engine can run into serious problems in the high RPM range.

Cheers, Owen

[river]

Hi,

No. It's just to get the best performance out of the engine is with a pot per cylinder, and not a single down-draught - or any single carby. If you can find a manifold to bolt one to a RG then it will probably work, but it won't have the performance of having a throat per cylinder.

seeyuzz
river

[o_man_ra23]

IE it will suffer at high RPM... dont listen to River, he doesnt realise that these engines rev past 3500rpm

So yeah, as I sed, it will idle, and rev to River speeds... but beyond that youve got a grenade waiting to go off. You wouldnt put a lumpy cam in a 351 then put a 250x-flo carby on would you??

Cheers, Owen

[river]

Hi,

IE it will suffer at high RPM... dont listen to River, he doesnt realise that these engines rev past 3500rpm

They can go faster than 3500rpm!!!! I wondered why there were all these extra numbers on the tacho. One day, where no one is around and it's safe, I may just see if I can get it over the magical 3500 mark.

I'll see if I can push it to 4000!!!!!! <snigger...... snigger>

But then it goes in for a service and full rebuild in case I've stressed anything.

seeyuzz
river

[o_man_ra23]

Oh, one day before you retire from driving and pass the 25 to me, you will learn why the tacho has a reading of 7000rpm

You shouldnt leave that too late tho, might cause a heart attack... and we wouldnt want that

Cheers, Owen

[Screamn_Sleeka]

It will be FINE with a single "normal" carby. But use a 32/36 weber or something decent instead of the rubbish 18R-C one. Im not suggesting a 32/36 as a performance carby, as its not, its jsut a plain carby that is easy to use and has no vacuum operation's.

Just make the manifold out of pipes.
There is nothing special about the 18R-G that needs the solex's, you'll get much better economy with a normal carby. And 18R-G's are only good for putting along so there is no point in wasting the fuel.

[MWP]

MWP, its called lumpy cams. These engine work best with virtually zero runners (ITBs), so anything hampering the flow will net a bad result... and your engine can run into serious problems in the high RPM range.

So all those big V8s running lumpy cams and down draught carbs must suck!

... sorry, but this doesnt make any sense to me at all.
In fact, by my thinking, lumpy camed engines should run better with down draught carbs as they will see a more consistent air flow and therefore meter fuel better at low revs.

But you are right of course about running an 18RC carb on a 18RG... it will choke higher up the rev range.
Not just that either... the 18RC carbs are just crap, they dont meter fuel well at all.

Mike, get along to your nearest u-pull-it and grab the carb + manifold off a XE/XF falcon (the ones with the Weber 34ADM carb).
The carb itself its very good and ive also heard of someone bolting the manifold with two runners cut off onto an 18RG.
Itll cost you $40 max.
Dodgy, yes, but itll work a lot better than the 18RC carb.

[o_man_ra23]

Screamer... ever felt the velocity that air gets sucked through the 40mm Solexs at 3000ish rpm from an 18RG?? I tell you its a lot more than most 2Ltr motors would suck. A 32/36 would be a huge restriction, and thats not good for bearings, rings or mixtures... as the carbies rely on air velocity to suck in/vapourise the fuel. Basically you would end up with a really rich mixture, that burns lean because the fuel sorta comes in in droplets instead of vapour.

Cheers, Owen

[o_man_ra23]

MWP... V8s have a fairly direct path from the carby to the intake, the fact the heads are on an angle ensure this. Performance V8s will often use straight intakes which are at the same angle as the heads, with ITBs... they also have space issues to worry about, and I havent come across too many which make decent HP/Ltr numbers without being a quad cam injected motor.

18RGs dont do much at low RPM, so as it might be smoother there to have a more consistent airflow, the engine is designed to run at high RPM, where the extra airflow impedence is a problem.

Cheers, Owen

[MWP]

Screamer... ever felt the velocity that air gets sucked through the 40mm Solexs at 3000ish rpm from an 18RG?? I tell you its a lot more than most 2Ltr motors would suck.

Every 4stroke 4cyl 2000cc engine running at 3000RPM will draw the same amount of air.
Its physics.
Yes, VE comes into play, but it doesnt make that big a difference.